Exposure to high levels of ionizing radiation can be harmful. Measuring the level of an individual's exposure can be useful in allocating resources and determining appropriate methods of treatment. In some circumstances, it can be useful to determine the exposure of an entire population to a source of ionizing radiation, for example, in mass-casualty radiation accidents, or in incidents of radiological terrorism (Alexander G. A. et al., Biodos-EPR-2006 Meeting: Acute dosimetry consensus committee recommendations on biodosimetry applications in events involving uses of radiation by terrorists and radiation accidents. Radiation Measurements 42 (2007) 972-996).
First responders and receivers (i.e. physicians and nurses) need guidance to perform triage based on dose assessment, so that those who are at risk of significant acute radiation effects are identified and entered into the health care system. For example, individuals with sub clinical exposures (for example, less than about 1.5 Gy) can be followed as outpatients. Individuals with significant absorbed doses (for example, in the range of about 1.5-10 Gy) can be referred to hospitals for treatment, while those with higher absorbed doses (for example, greater than about 10 Gy) may be triaged for compassionate care or to heroic measures, if resources are available. Dose assessments can contribute to medical treatment decisions.
Several techniques exist that are useful to estimate the level an individual may have been exposed to ionizing radiation. These include cytogenetic assays, electron spin resonance (ESR) or electron paramagnetic resonance (EPR), and luminescence techniques.
Cytogenetic assays measure the effects of ionizing radiation on the cells of an exposed individual. These assays include culturing cells from an individual, then visualizing chromosomal aberrations in such cells. Cytogenetic assays are therefore invasive, expensive, and time-consuming.
ESR detects free electrons produced in the tissues of an individual on exposure to high levels of ionizing radiation. Generally, ESR cannot be carried out in the presence of large amounts of water and had therefore been limited to relatively dry samples, such as extracted teeth. Recently, ESR has been applied to tissues such as fingernail and toenail parings (Romanyukha A. et al., EPR dosimetry in chemically treated fingernails. Radiation Measurements (2007) 42:1110-1113; Trompier F. et al., Protocol for emergency EPR dosimetry in fingernails. Radiation Measurements (2007) 42:1085-1088; and Trompier F. et al., Electron paramagnetic resonance radiation dosimetry in fingernails. Radiation Measurements (2009) 44:6-10).